The Statistics and Health Economics Core of the San Francisco Treatment Research Center provides full and ongoing supports for three central and critical activities ofthe Center;data management, statistical, and economic analysis. The specific aims are;(1) To provide data management by supplying structure, support, coordination and oversight for the collection, computer entry, and tracking of research data, including the security and integrity of all Center data. (2) To provide methodological consultation and biostatistical analyses for each component. (3) To conduct research into quantitative methods designed to enhance Center-wide research. (4) To assess the cost of innovative treatments and the impact of the innovations on other health care costs incurred, to value treatment outcomes using economic models and to combine these data in cost-effectiveness analyses. The Core will also take the lead on three planned studies of the complexity of types of cigarette smokers, a meta-analysis, and a cross-cutting economic study. By the very nature of our work this Core is intimately tied to the theme of the Center as a key resource for all proposed Center components including the cross-component studies. Research on continuing and complex treatment for complex patients requires the collection, management, and analysis of complex datasets. In concert with the theme we use rigorous methodology, much of it derived from clinical trials, combine efficacy and costeffectiveness analysis, do work that bridges the gap between treatment and services research and analyze relations between multiple risk factors, both as predictors and time dependent covariates. This Core supplies the quantitative activities of all component studies and integrates its work with the Scientific and Administrative Core.